Haynes L, Fuller L, McKinney E C
Department of Microbiology and Immunology, University of Miami School of Medicine.
Dev Comp Immunol. 1988 Summer;12(3):561-71. doi: 10.1016/0145-305x(88)90072-9.
Fc receptors for shark IgM have been demonstrated on shark leukocytes. Measurement of receptor binding required treatment of leukocytes with Cytochalasin D to inhibit phagocytosis. EA rosetting assays were carried out using human erythrocytes coated with shark anti-human antibody. Binding to shark leukocytes was demonstrated to be specific to shark IgM in that affinity purified shark IgM and purified Fc5 mu fragments could block rosette formation, but not shark transferrin, bovine serum albumin or fetal bovine serum. The binding was shown to be saturable and reversible, characteristic of receptor-ligand interaction. Further, it was shown that affinity purified, radioiodinated IgM could also bind Cytochalasin D-treated shark leukocytes in a manner analogous to rosetting. We conclude that Fc receptors appeared early in evolution, and that previous difficulties in demonstrating the Fc mu receptor resulted from non-specific binding associated with phagocytosis.
鲨鱼白细胞上已证实存在鲨鱼IgM的Fc受体。受体结合的测定需要用细胞松弛素D处理白细胞以抑制吞噬作用。使用包被有鲨鱼抗人抗体的人红细胞进行EA玫瑰花结试验。已证明与鲨鱼白细胞的结合对鲨鱼IgM具有特异性，因为亲和纯化的鲨鱼IgM和纯化的Fc5μ片段可阻断玫瑰花结的形成，但鲨鱼转铁蛋白、牛血清白蛋白或胎牛血清则不能。这种结合表现出饱和性和可逆性，这是受体 - 配体相互作用的特征。此外，还表明亲和纯化的、放射性碘化的IgM也能以类似于玫瑰花结形成的方式结合经细胞松弛素D处理的鲨鱼白细胞。我们得出结论，Fc受体在进化过程中出现得很早，并且先前在证明Fcμ受体时遇到的困难是由与吞噬作用相关的非特异性结合导致的。
